From a curious paper just published in the The Neuroscientist entitled “Plastering the Head with Crushed Snails to Treat Pediatric Hydrocephalus: An Ancient Therapy with a Pharmacological Basis.”
In the Middle Ages, medical therapy for pediatric hydrocephalus [a condition caused by the accumulation of cerebrospinal fluid inside the brain that can lead to enlargement of the head] was characterized by the application of drying substances to decrease the size of the heads of affected children.
A poultice of crushed snails applied to the head was considered to be one of the most powerful therapies for reducing swelling caused by excessive humors. Incunabula (texts printed in Europe before 1501 CE) and Renaissance texts document the extended use of this therapy, which was considered by physicians to be effective and less dangerous than surgical treatment…
It has been demonstrated that snails and slugs possess high concentrations of glycosaminoglycans and mucopolysaccharides…
Therefore, we think that the ancient practice of plastering the head with crushed snails in pediatric hydrocephalus, although not based on science as we know it, may have had at least some basis.
Negatively charged glycosaminoglycans absorb and retain large amounts of water and are important components of connective tissue. Because of these properties, glycosaminoglycans are currently used under various conditions to rehydrate the skin.
Link to closed access paper in The Neuroscientist.